Nested-based manufacturing, when it works and when it doesn't

There has been a lot of talk in recent months about nested-based manufacturing, or NBM. NBM is an example of a methodology that has been around for a number of years in other industries, such as sheet metal and garment cutting industries. In its purest form, nested-based manufacturing means producing all of the parts needed for a product from a single sheet of wood, particleboard, sheet metal, fabric, etc.

In recent years, nested-based manufacturing has become joined with cellular manufacturing, JIT principles and CAD/CAM technology to form a manufacturing philosophy.

Who can use nested-based manufacturing?

The most common users of NBM are:

cabinet manufacturers,

store fixture manufacturers,

display manufacturers,

casegood manufacturers and

RTA manufacturers.

In short, anyone who makes panel based products is a possible candidate for NBM.

For example, let's say we are going to make a double-pedestal desk.

We are able to get all the parts for the interior carcass out of a single 4 x 8 panel of 3/4-inch-thick board. The top (which might be a thicker 1-1/8-inch board), is on a second panel, and the back panel is located on a third sheet. In this case, I have assumed that my back panels are pretty common, so I went ahead and cut two out of this panel. I was once part of a team that set up this type of system, so I can give some insight into the benefits and challenges of the concept.

Advantages of nested-based manufacturing

1. Reduced product cycle time - The big advantage of NBM is that all the parts for a product are produced at the same time, so there is no concern of the timing of different parts showing up at the assembly department. Companies today understand the power of inventory turns and the need to turn raw materials into sold goods as quickly as possible. However, under traditional batch manufacturing, it is very difficult to make sure that all these parts will be made in the correct order. Producing the unit as a whole greatly reduces the time from an order being sent to the floor to it going out the door.

2. Reduced W-I-P - As you reduce the product cycle time, the need for work-in-process is reduced. Because inventory costs money, the opportunity to improve your cash flow and return on investment is enhanced.

3. Higher consistency - Because all the parts are manufactured on a CNC machine, consistency is improved.

Disadvantages

1. Capital investment - Putting in the type of system we are talking about here is not cheap. There is the cost of the CNCs of course, but unless your factory already has them, you will also have to pick up some additional equipment to handle horizontal machining and edge treatments as discussed below. Depending on what equipment you have to purchase and what you already have, you can expect the costs to run $150K plus.

2. Horizontal machining - Because the parts are machined as a sheet, it is difficult or impossible to perform edge processes on the machine. Some CNCs can be equipped with horizontal boring machines, sanding heads and even edgebanding aggregates. However, these heads are of limited use in an NBM system. My feeling is that edgebanding and sanding are still not practical for most processes.

3. Cost justification - It's very difficult to say whether or not NBM cells make sense for your company. A lot of the decisions would be affected by what kind of existing equipment you have, how much redesign would be required for your products to work in an NBM system, and whether your customer base would accept such redesigns.

Nested-based manufacturing should certainly be investigated by anyone considering a new plant or plant expansion. Who knows, it might make sense for your company. However, companies should evaluate it in the same way they evaluate any new investment - what's it going to add to my bottom line, and how much is it going to cost me?

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